Conventional collapsible tube frame wheelchairs typically comprise metal left and right side frame weldments which are laterally interconnected by either one or two scissoring “X” braces. Lower ends of the “X” brace or braces of such a conventional wheelchair are typically pivotally attached to lower longitudinally extending members of the side frame weldments, while the upper ends of the “X” brace or braces are rigidly attached to left and right longitudinally extending sling seat suspending “T” bars. Forward and rearward ends of such “T” bars typically slidably engage vertically extending tube members of the left and right side frames, and a flexible sling seat typically spans between the “T” bars. As a user of such conventional wheelchair sits upon the sling seat, the left and right “T” bars are drawn and slidably guided downwardly within the left and right frame weldments, resulting in simultaneous downward scissoring and lateral splaying the “X” brace, laterally articulating the wheelchair to a width sufficient to accommodate the seated user. Alternately, in order to compactly collapse such conventional wheelchair, the left and right side frame weldments are manually drawn together, upwardly scissoring the “X” brace while simultaneously flexibly folding the sling seat and slidably moving the “T” bars and sling seat upwardly with respect to the side frame weldments.
A problem or deficiency associated with such conventional tube frame/“X” brace collapsible wheelchairs is that neither leg of the “X” brace is capable of pivoting to an orientation which is in closely articulated proximity with the side frame member from which the leg extends. In its maximally collapsed configuration, both legs of such “X” brace continue to extend angularly away from its side frame. Such limitation upon “X” brace leg pivoting action results in an undesirable limitation upon the wheelchair's ability to compactly laterally collapse.
In addition to a capability for compact collapsibility, wheelchairs are also desirably light in weight. A commonly known means for reducing the weight of metal tube weldments, without unduly compromising strength characteristics, is to increase the diameter of tube members of the structure, while dramatically decreasing tube wall thickness. Such design approach beneficially reduces the overall mass of the weldment. However, such approach to lightening tube frame structures is problematic when applied to collapsible wheelchairs because increasing the diameters of the frame's tube members further interferes with or disrupts the desirable compact collapsibility function.
The instant inventive collapsible wheelchair frame solves or ameliorates problems discussed above by providing a unique and novel hinged assembly of preferably lightweight yet strong panels or plates which are capable of alternately outwardly articulating to a rigid wheelchair box frame or chassis configuration and collapsing to a compact wheelchair storage configuration, such collapsing capability preferably approaching a compact stacked panel configuration.